SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3740085a28d8ebf6b959f32b54bd1071626a6e556719c36159a77bb0de3e1cdc' 
  AND token = 'vKiZf30wKgV+ELmgylwfpBSAYh1Ss8qq0hGzblHLKJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}